A backup, emergency generator at the San Onofre nuclear plant might have been tampered with, plant operator Southern California Edison reported to the Nuclear Regulatory Commission this week.

The diesel generator in the Unit 3 reactor was found to have coolant in its oil system late in October, and the problem was reported to the NRC Oct. 30.

Both of San Onofre's reactor units remain offline, Edison says, so the problem presented no danger to plant workers or the public.

But on Thursday, Edison released a statement saying it had reported to the NRC on Nov. 27 that "an internal investigation found evidence of potential tampering as the cause of this abnormal condition."

"The evidence is not conclusive that it's tampering," said Edison spokeswoman Jennifer Manfre said Thursday. "But of course we are doing a very thorough investigation, so that has not been ruled out."

She declined to comment further, citing security reasons, although the Edison statement said security had been increased at San Onofre because of the incident.

If the plant were running, the generator would be used to supply backup power in case of an emergency, such as an earthquake, she said. But the generator itself was down for maintenance, so even if the plant were running last month, it would not have been used for emergency power.

Gary Headrick, co-founder of the environmental group, San Clemente Green, called attention to the tampering issue in an email he sent out Thursday.

Headrick said Thursday that he learned of the tampering report from employees at the plant.

"We're waiting to see what happens tomorrow," Headrick said. "I think this is so incredible."

On Friday, a group of Buddhist monks are expected to walk from Dana Point to the San Clemente Pier, then begin a six-day fast; Headrick said the idea is to pray for the safety of people who live around the plant.

Also Friday, Edison and the NRC will hold a meeting, open to the public, to discuss Edison's plan to restart the Unit 2 reactor at low power.

The restart has not been approved by NRC, and if it happens it will likely be months away.

Both of San Onofre's reactors have been offline since January. Unit 2 had been shut down for maintenance when a small leak of radioactive gas prompted shutdown of Unit 3 on Jan. 31.

Inspections showed extensive wear on steam generator tubes in both reactor units, later traced to design flaws in the generators, replaced between 2009 and early 2011 in a $671 million operation.

The lower-power start of Unit 2, Edison says, would eliminate the vibrations believed to have caused the excessive wear.

User Agreement

Keep it civil and stay on topic. No profanity, vulgarity, racial
slurs or personal attacks. People who harass others or joke about
tragedies will be blocked. By posting your comment, you agree to
allow Orange County Register Communications, Inc. the right to
republish your name and comment in additional Register publications
without any notification or payment.